L-PI-16-051, 10 CFR 50.46 Emergency Core Cooling System Annual Report

10 CFR 50.46 Emergency Core Cooling System Annual Report

ML16175A638
Person / Time
Site:	Prairie Island
Issue date:	06/22/2016
From:	Northard S Northern States Power Co, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-PI-16-051
Download: ML16175A638 (11)

Text

(l Xcel Energy JUN 2 2 2016 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 10 CFR 50.46 ECCS Annual Report L-PI-16-051 10 CFR 50.46

References:

1) K. Davison, PINGP, letter to NRC Document Control Desk, 201410 CFR 50.46 LOCAAnnual Report, L-PI-15-061, 6/30/2015 (ADAMS Accession No. ML15181A080)

Pursuant to 10 CFR 50.46(a)(3)(ii), Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM") submits the annual report of changes to or errors in and estimated effects on the Prairie Island Nuclear Generating Plant (PINGP) Units 1 and 2 Emergency Core Cooling System (ECCS) analyses (Enclosure 1 ). The limiting loss of coolant accident (LOCA) analysis for PINGP Units 1 and 2 is the large break LOCA (LBLOCA) analysis.

The peak cladding temperature (PCT) for the LBLOCA analysis is unchanged for PINGP Units 1 and 2 since the last annual report (Reference 1 ). Summary of Commitments This letter contains no new commitment and no revision to an existing commitment.

Scott Northard Acting Site Vice President, Prairie Island Nuclear Generating Plant Northern States Power Company-Minnesota Enclosure (1) 1717 Wakonade Drive East

• Welch, Minnesota 55089-9642 Telephone:

651.388.1121 NRC Document Control Page 2 cc: Regional Administrator, Region Ill, USNRC Project Manager, Prairie Island Nuclear Generating Plant, USNRC Resident Inspector, Prairie Island Nuclear Generating Plant, USNRC ENCLOSURE 1 10 CFR 50.46 LOCA Annual Report 8 pages follow Westinghouse Non-Proprietary Class 3 @ Westinghouse Westinghouse Electric Company Engineering Center of Excellence 1 000 Westinghouse Drive Cranberry Township, Pennsylvania 16066 USA Direct tel: (412) 374-5598 e-mail: mcmillh@westinghouse.com Our ref: LTR-LlS-16-40 February 18,2016 Prairie Island Units 1 and 2 10 CFR 50.46 Annual Notification and Reporting for 2015

Dear Sir or Madam:

This is a notification of 10 CFR 50.46 reporting information pertaining to the Westinghouse Electric Company Evaluation Models/analyses.

As committed to in WCAP-13451, Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting, Westinghouse is providing an Annual Report for Emergency Core Cooling System (ECCS) Evaluation Model changes and errors for the 2015 model year. All necessary standardized reporting pages for any changes and errors for the Evaluation Models utilized for your plant(s) are enclosed, consistent with the commitment following the NUPIC audit in early 199?. Peak Clad Temperature (PCT) sheets are enclosed.

All necessary revisions for any non-zero, non-discretionary PCT change to Section C have been included.

Non-discretionary PCT impacts pf ooF will generally not be presented on the PCT sheet. Any plant-specific errors in the application of the model for 2015 will also be provided in Section C with discussion enclosed or cited. The Evaluation Model changes and errors (except any plant-specific errors in the application ofthe model) will be provided to the NRC via Westinghouse letter. This information is for your use in making a determination relative to the reporting requirements of 10 CFR 50.46. The information that is provided in this Jetter was prepared in accordance with Westinghouse's Quality Management System (QMS). Ple!!-se contact your LOCA plant cognizant engineer (PCE), Dania] Utley ( 412-3 7 4-6663), if there are any questions concerning this information.

Author: (Electronically Approved)*

Heather McMillen LOCA Integrated Services II Approved: (Electronically Approved)*

Matthew B. Cerrone Manager, LOCA Integrated Services II Verified:

Attachment:

10 CFR 50.46 Reporting Text and PCT Summary Sheets (7 Pages) . (Electronically Approved)*

Dania! W. Utley LOCA Integrated Services II *Electronically appro1*ed records are authenticated in the elecn*onic document management system. © 2016 Westinghouse Electric Company LLC All Rights Resen*ed Page 14 of 36

.Attachment"to LTR-LIS-16-40 GENERAL CODE MAINTENANCE Background February 18,2016 Page 1 of7 Various changes have been made to enhance the usability of codes and to streamline future analyses.

Examples of these changes include modifYing input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. These changes represent Discretionary Changes that will be implemented on a fit basis in accordance with Section 4.1.1 ofWCAP-13451.

Affected Evaluation Model(s) 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The nature of these changes leads to an estimated Peak Cladding Temperature (PCT) impact of 0°F. Page 15 of36 Attachment to LTR-LIS-16-40 February 18, 2016 Page 2 of7 PRAIRIE ISLAND UNIT 1 EARLIER CONTAINMENT SPRAY ACTUATION TIMES DUE TO DEGRADED FAN COOLER HEAT REMOVAL CAPACITY Background Due to the design of the Prairie Island emergency core cooling system (ECCS), a complete inte1mption in high head safety injection (HHSI) flow can occur during the switchover to sump recirculation for the small break Joss-of-coolant accident (SBLOCA) transient.

The Prairie Island Unit 1 SBLOCA analysis of record (AOR) models the actuation timing of the containment spray system based on containment pressurization calculations for the smaller break sizes considered therein (1.5-inch and 2-inch breaks). This ultimately-dictates the timing of the switch over to sump recirculation and corresponding HHSI flow interruption.

Prairie Island Unit 1 identified a potential degradation in containment fan cooler heat removal capacity.

Updated containment pressurization calculations result in earlier containment spray actuation times due to the degraded heat removal capacity of the fan coolers. This scenario is characterized as a change in plant configuration, distinguished from an evaluation model change in Section 4 of Affected Evaluation Model(s) 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect When considering the reduced heat transfer capability of the fan coolers, the containment spray pumps actuate earlier than modeled in the AOR for the 1.5-inch and 2-inch breaks; however, the inte1Tuption during the switchover to sump recirculation still occurs after the core has recovered.

There is sufficient reactor coolant system inventory during the flow interruption such that a post-switchover core uncovery would not occur. Therefore, this issue is estimated as a 0°F peak cladding temperature (PCT) impact on the Prairie Island Unit 1 SBLOCA AOR. Page 16 of36 Attachment to L TR-LIS-16-40 February 18,2016 Page 3 of? Westinghouse LOCA Peak Clad Temperature Summary for ASTRUM Best .Estimate Large Break Plant Name: Utility Name: Revision Date: Prairie Island Unit 1 Xcel Energy, Inc 2/112016 Analysis Information EM: ASTRUM (2004) Analysis Date: FQ: 2.5 FdH: Fuel: 422 Vantage+ SGTP(%): Notes: 11/30/2007 1.77 10 Limiting Break Size: Split Clad Temp (OF.) Ref. LICENSING BASIS Analysis-Of-Record PCT PCT ASSESSMENTS (Delta PCT) A. PRIOR ECCS MODEL ASSESSMENTS I . Evaluation of Fuel Pellet Thennal Conductivity Degradation and Peaking Factor Bumdown 2 . Revised Heat Transfer Multiplier Distributions 3 . Error in Burst Strain Application B. PLANNED PLANT MODIFICATION EVALUATIONS 1 . None C. 2015 ECCS MODEL ASSESSMENTS I . None D. OTHER* I . None LICENSING BASIS PCT + PCT ASSESSMENTS PCT= 1765 227 -2 25 0 0 0 2015 It is recommended that the licensee determine if these PCT allocations should be considered with respect to 10 CFR 50.46 reporting requirements.

References 1 2 3 4 Notes (a) 1 . WCAP-17783-P, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for Prairie Island Units 1 and 2 with Replacement Steam Generators Using ASTRUM Methodology," June 2013 .. Notes: 2 . LTR-LIS-12-414, "Prairie Island Units I and 2, 10 CFR 50.46 Notification and Reporting for Fuel Pellet Thennal Conductivity Degradation and Peaking Factor Burndown," September 20,2012. 3 . LTR-LIS-13-366, Revision 1, "Prairie Island Units I and 2 10 CFR 50.46 Report for Revised Heat Transfer Multiplier Distributions," August 2013. 4 . LTR-LIS-14-50, "Prairie Island Units I and 2 10 CFR 50.46 Report for the HOTSPOT Burst Strain Error Correction," January 2014. (a) 1l1is evaluation credits peaking factor bumdown, see Reference

2. Page 17 of 36 Attachrnerifto LTR-LIS-16-40 Westinghouse LOCA Peak Clad Temperature for Appendix K Small Break Plant Name: Utility Name: R,evision Date: Prairie Islarid Unit l Xcel Energy, Inc 2/I/2016 Analysis Information EM: NO TRUMP Analysis Date: FQ: 2.5 FdH: Fuel: 422 Vantage+ SGTP (%): Notes: Zirlo ( l4X 14), Framatome RSG LICENSING BASIS Analysis-Of-Record PCT PCT ASSESSMENTS (Delta PCT) 1/21/2008 1.77 10 A. PRIOR ECCS MODEL ASSESSMENTS I . None B. PLANNED PLANT MODIFICATION EVALUATIONS I . None C. 2015 ECCS MODEL ASSESSMENTS I . None D. OTHER* I . None LICENSING BASIS PCT + PCT ASSESSMENTS Limiting Break Size: Clad Temp (°F) 959 0 0 0 0 PCT= 959 February 18,2016 Page 4 of7. 3 inch Ref. Notes It is recommended that the licensee determine if these PCT allocations should be considered with respect to I 0 CFR 50.46 reporting requirements.

References 1 . L TR-LIS-08-158, "Transmittal of Future Prairie Island Units 1 and 2 PCT Summaries," February 2008. Notes: None Page 18 of36 Attachment to L TR-LIS-16-40 February 18,2016 Page 5 of7 Westinghouse LOCA Peak Clad Temperature Summary for ASTRUM Best Estimate Large Break Plant Name: Utility Name: Revision Date: Prairie Island Unit 2 Xcel Energy, Inc 2/112016 Ana.lysis Information EM: ASTRUM (2004) Analysis Date: FQ: 2.5 FdH: Fuel: 422 Vantage+ SGTP(%): Notes: 11/30/2007 1.77 10 Limiting Brcllk Size: Split Clad Temp (DF) Ref. LICENSING BASIS Analysis-Of-Record PCT PCT ASSESSMENTS (Delta PCT) A. PRIOR ECCS MODEL ASSESSMENTS . Evaluation of Fuel Pellet Thennal Conductivity Degradation and Peaking Factor Bumdown 2 . Revised Heat Transfer Multiplier Distributions 3 . Error in Burst Strain Application B. PLANNED PLANT MODIFICATION EVALUATIONS I . None C. 2015 ECCS MODEL ASSESSMENTS I . None D. OTHER* I . None LICENSING BASIS PCT + PCT ASSESSMENTS 1765 227 -2 25 0 0 0 PCT= 2015 It is recommended that the licensee detennine if these PCTallocations should be considered with respect to I 0 CFR 50.46 reporting requirements.

References 2 3 4 Notes (a), (b) I . WCAP-17783-P, "Best-Estimate Analysis of the Large-Break Loss-of-Coolant Accident for Prairie Island Units I and 2 with Replacement Steam Generators Using ASTRUM Methodology," June 2013. Notes: 2 . LTR-LIS-12-414, "Prairie Island Units I and 2, 10 CFR 50.46 Notification and Reporting tbr Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Bum down, September 20, 2012. 3 . LTR-LIS-13-366, Revision I, "Prairie Island Units 1 and 2 10 CFR 50.46 Report for Revised Heat Transfer Multiplier Distributions," August 2013.

• 4 . LTR-LIS-14-50, "Prairie Island Units I and 2 10 CFR 50.46 Report for the HOTSPOT Burst Strain Error Correction," January 2014. (a) This evaluation credits peaking factor bumdown, see Reference

2. (b) The reporting text and line item originally identified for Unit I in Reference 2 is applicable to Unit 2 with RSGs. Page 19 of 36 Attachment to L TR-LIS-16-40 February 18,2016 Page 6 of7 Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Small Break Plant Name: Utility Name: Revision Date: Prairie Island Unit 2 Xcel Energy, Inc 2/112016 Analysis Information EM: NOTRUMP Analysis Date: 1/21/2008 1.77 Limiting Brealc Size: 3 inch FQ: 2.5 FdH: Fuel: 422 Vantage+ SGTP (%): 10 Notes: Zirlo (14Xl4), AREVA RSG LICENSING BASIS Analysis-Of-Record PCT PCT ASSESSMENTS (DiMa PCT) A. PRIOR ECCS MODEL ASSESSMENTS I . None B. PLANNED PLANT MODIFICATION EVALUATIONS 1 . None C. 2015 ECCS MODEL ASSESSM!£NTS I . None D. OTHER* 1 . None LICENSING BASIS PCT + PCT ASSESSMENTS Clad Temp (OF) 959 0 0 0 0 PCT= 959

• It is recommended that the licensee determine if these PCT allocations should be considered with respect to I 0 CFR 50.46 reporting requirements.

References 1 . LTR-LIS-08-158, "Transmittal of Future Prairie Island Units 1 and 2 PCT Summaries," February 2008. Ref. l, 2 2 . LTR-LlS-13-274, "Prairie fslalld Units I and 2, 10 CFR 50.46 Summary Sheets for the Evaluation to Support the Unil2 Installation of AREVA Model 56119 Replacement Steam Generators (RSGs)," June 2013. Notes: (a) The Unit I AOR is applicable to Unit 2 with the RSGs installed.

Page 20 of36 Notes a Attachment to L TR-LIS-16-40 10 CFR 50.46 Reporting SbarePoint Site Check: EMs applicable to Prairie Island: Realistic Large Break-ASTRUM (2004) Appendix K Small Break-NOTRUMP 2015 Issnes Transmittal Letter Issue Description February 18, 2016 Page 7 of7 L TR-LIS-16-60 10 CFR 50.46 Report for Earlier Containment Spray Pump Actuation Times due to Degraded Fan Cooler Heat Removal Capacity Page 21 of 36